Tuning mechanism for hollow electrical resonators



Mgrch 21, 1950 N. c. BARFORD TUNING MECHANISM FOR HOLLOW ELECTRICALRESONATORS Filed Sept. 15, 1945 //v VE/VTOE. NORMAN (HA/e455 84 RFOQD.

By 7%.4W

A rap/v04 Patented Mar. 21, 195

UNITED STATES PATENT OFFICE TUNING MECHANISM FOR HOLLOW ELECTRICALRESONATORS signor to Electric &

Great Britain England, a company of Application September 15, 1945,Serial No. 616,620 In Great Britain July 13, 1944 Section 1, Public Law690, August 8, 1946 Patent expires July 13, 1964 4 Claims. (Cl. 74-479)This invention relates to tuning mechanism for hollow electricalresonators such as are employed in electron discharge devices of thevelocity-modulation type or for other purposes.

Such resonators can be tuned in a variety of manners and variousmechanisms have heretofore been proposed for that purpose. It is alsodesirable for the mechanism to afford a coarse and fine tuning controland several proposals have been made for effecting such control, such asthe provision of differential screws, differential levers and the like.Most of these prior proposals have, however, been found to beunsatisfactory in practice mainly due to difficulty of manufacture owingto the accuracy required, especially when used with very smallresonators, multiplicity of parts and sensitivity to finger pressurewhen operating the mechanism.

The object of the present invention is to provide an improved mechanismfor tuning a hollow resonator which will afford coarse and fine tuningand which will overcome or reduce the. above-mentioned disadvantageswhich arise with the known forms of tuning mechanism.

According to the invention there is provided a tuning mechanism for ahollow electrical resonator comprising a pivotally-mounted adjustableelement, means for causing said element to pivot about a plurality ofaxes and means for communicating the motion of said element to theadjustable part of said resonator so as to cause tuning of saidresonator, the arrangement being such that pivotal movement of saidelement about one of said axes serves to effect a coarse adjustment ofsaid part whilst movement about another axis serves to effect a fineadjustment of said part.

In order that the said invention may be clearly understood and readilycarried into effect it will now be more fully described with referenceto the accompanying drawings in which- Figure l is a plan view of atuning mechanism according to the invention,

Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1,and looking in the direction of the arrows, and

Figure 3 is an explanatory diagram for explaining the operation of themechanism shown in Figures 1 and 2.

Referring now to Figures 1 and 2 of the drawings, the tuning mechanismshown is employed by way of example to cause deflection of the wall 4 ofa hollow toroidal resonator 5 so as to cause a change of tuning mainlyby varying the width of the gap at the centre of the resonator. The

2 tuning mechanism can however be employed to effect tuning of theresonator in any other suitable manner. The resonator 5 is shown locatedand supported by means not shown, in an envelope, part of which isindicated at 6 and the wall 4 is connected by a rod 1 to a flexiblediaphragm 8 by means of which movement can be communicated to the Wall 4from the exterior of the envelope 6 whilst maintaining the space withinthe envelope 6 vacuum or gas-tight. The tuning mechanism shown comprisesan adjustable element 9 in the form of a ring surrounding the envelope6, the ring 9 being pivotally-mounted on a pivot in the form of apointed screw l0 which is threaded into a support If in the form of aring rigidly secured relatively to the envelope 6. Pivotal movement ofthe ring 9 is communicated to the diaphragm 8 and thus to the wall 4 ofthe resonaor by a rod l2 having pointed ends, one end of which engagesin a suitably-shaped depression in the ring 9 and the other end of whichengages in a suitably-shaped depression formed in an actuating member [3which is hingedly mounted at 14 to a support [5 secured to the rigidring II. The actuating member I3 is connected to the diaphragm 8 by arod it, as indicated. The rod l2 extends through an aperture I! in therigid ring II and it will be appreciated therefore that when the ring 9is caused to move about the pivot ID the rod l2 will be movedsubstantially axially causing the actuating member [3 to turn about itshinge 14 thereby causing the rod IE to move substantially axially so asto cause the wall 4 to move towards or away from the opposite wall ofthe resonator. Pivotal movement of the ring 9 is arranged to effect botha coarse and fine control of tuning. In order to effect a fine controlof tuning an adjusting screw I8 is provided having a knurled knob IS,the screw [8 being threaded into the rigid ring H and having a pointedend bearing against the ring 9. In order to effect a coarse control oftuning a similar screw is provided having a knurled knob 29 and which isalso threaded into the rigid ring H and having a pointed end bearing onthe ring 9. Since as will hereinafter appear the pivotal movement of thering 9 is greater under the action of the screw for effecting a coarsecontrol compared with its movement when actuated by the screw 18, it ispreferred to provide a channel in the ring 9 with which the pointed endof the coarse control screw engages the channel being suitably arrangedalong the line AB, Figure 3, hereinafter more fully referred to so as toallow the ring 9 to move more freely relatively to the point of thescrew and to locate the axis about which the ring 9 pivots for finecontrol. The ring 9 is maintained in contact with the pivot 10 and therod I2 by means of a number of compression springs 2!, these compressionsprings being disposed between the lower surface of the ring 9 and theheads of bolts 22 which are threaded into the rigid ring H and securedby nuts 23. Tension springs between the rings 9 and H couldalternatively be used. The actuating member 13 is maintained in contactwith the upper endofthe-rod l2 by means of tension springs 24 which aresecured to the end of a cross bar 25 attachedto the actuating member l3,the springs 24 passing through apertures 26 in the ring II and beinganchored to the ring 9.

The disposition of the coarse and fine adjusting screws is so arrangedin relation to the pivot as to cause the ring -9 to pivot about twoaxes, pivotal movement about one axis effecting a coarse control oftuning and pivotal movement 'abou't'the other axis causing afine controlof tuning. In order to expl'ainhow the coarse and "fine control oftuningis 'e'fiected, reference will now be made tofFigure 3 ofithe drawings inwhich the point "Acorres'ponds to the point where the coarse controlscrew engages the ring II, the point B corresponds to'the'pivot formedby the screw l llandthe point'Ccorresponds to the point where -the finecontrol screw [8 engages the ring '9. The point D corresponds to thepoint where the rod I2 engages the ring 9. The line IAQ'is perpendicularto line BC, the line CP is perpendicularto AB, the'lin'eDD is parallelto AB and the'lineDD is parallel to BC. If the points B and C are fixedand the point A is moved at right angles'to'the'plane of the paper, theplane ABC will pivot about the axis BC and the ratio of the movement'ofpoint D to that of point A will 1' be .Snnilarly, if points A'and'B arefixed and point 'C' is moved at rightang-lesto the plane of the (paper,the-plane 'AB'C wilLpivot about the axis and the ratio of movement ofpoint D' to "that of point C will be Thus, it is possible to obtain tworates of move- "ment of the point D, these rates being dependent -on therelative positions of the points A, B, C

and D. In Figure 3' the :point D is much closer to AB than to BC andthus moveinent of'the point C efiects a fine control and movement of"point A effects a coarse control. In Figure 3 thepointD isshown outsidethe triangle ABC although it will be appreciated that this is notessential sincethe point D may, if desired, be located inside thetriangle ABC according to the different rates of tuningrequired andaccording to the direction in which the point D is requiredadjustableelement-and said means being so constructed and arranged thatpivotal movement of said element about one of said axes serves to effecta coarse adjustment of said part whilst movement about another :axisserves to effect a fine adjustment of said part, said pivotallymountedadjustable element cooperating with three points of pivotation, two ofsaid points determining the axis about which said element 'pivots foreffecting a coarse adjustment of tuning and the third-point and one ofsaid two points determining the axis about which said element :pivots.for effecting a fine adjustment of tuning, a connecting member linkingsaid pivotally-mountedadjustable element and said ad- '15 jjustable partof said resonator, the location and arrangement of said connectingmember relative to said points 'Ebeing such as to determine the relativerates of movement of said part for coarse rand-fine tuning of saidresonator.

2. Tuning mechanism for a hollow electrical adjustable resonatorcomprising a pivotallymounted adjustable element, means for causing saidelement to pivot about -a'plurality of axes and means'f'or communicatingthe motion of said 2?, element to the adjustable part of said resonatorso as to cause tuning-ofsaid resonator, saidadjustable element and ,saidmeans being so constructedand arranged thatpivotal movement of saidelement about one tof-said axes serves to :0 effect a coarse adjustmentof said part whilst movement about another axis serves to effeota fineadjustment .of said part, said pivotallymounted adjustable "elementcooperating with three points of pivotation,-'two:of said pointsdetermining'the axis aboutwhich said element pivotsfor effecting a"coarse adjustment of tuning andthe third .point and one of saidtwopoints determining the axis about which said element pivots foreffecting :a fine adjustment of tuning, 40 a connecting member linkingsaid pivotallymounted adjustable element and said adjustable part ofsaid resonatoig'the 'locationand arrangement of said connectingi'memberrelative to said points being such 'asto determine the relative rates ofmovement of'saidpart for coarse and fine tuning of said resonator, saidpivotally- .mounted adjustablev element being in the form ofa ringsurrounding the axis of said resonator,

said ring bearing against. a'normally 'fixed' pivot and'cooperatingwith'two' adjustingscrews which determine in conjunction'with saidnormally fixed pivot" the axesaboutwhich said ring pivots.

"3. .Tuning .mechanismfor a'hollow electrical adjustable resonatorcomprising a pivotallyfio'mounted adjustable element means for causingsaid element to pivot about a'plurality ofaxes and meansforcommunicating themotion of said element to the adjustablepart of saidresonator-s0 as to cause tuningof-said-resonator, said adjustto ableelement and saidmeans being so constructed and arranged thatpivotalmovement otsaid e1ement about oneof said axesserves -toefiect acoarse adjustment of said part whilst movement about another aXisserves-to-effect a fine adjust- "-ment orsaid part; said 'pivotallymounted adjust- -ableelemeht cooperating with-three points ofpivotation,two of said points determining the axis about whichsaidelement-pivotsrror efiecting a coarse adjustment of tuning :andrthethird point and one of said two points determining-the axis about whichsaid'element pivots for effecting a "-fine adjustment of-tuning, :aconnecting member linking saidwpivotally-emounted adjustable ele- ':mentand said adjustable part :of said resonator, -1 the locationzandarrangement. of; said connecting member relative to said points beingsuch as to determine the relative rates of movement of said part forcoarse and fine tuning of said resonator, said pivotally-mountedadjustable element being in the form of a ring surrounding the aXis ofsaid resonator, said ring bearing against a normally fixed pivot andcooperating with two adjusting screws which determine in conjunctionwith said normally fixed pivot the axes about which said ring pivots,and a pivotally-mounted actuating member coupled to said adjustable partof said resonator, said connecting member extending between said ringand said actuating member.

4. Tuning mechanism for a hollow electrical adjustable resonatorcomprising a pivotallymounted adjustable element, means for causing saidelement to pivot about a plurality of axes and means for communicatingthe motion of said element to the adjustable part of said resonator soas to cause tuning of said resonator, said adjustable element and saidmeans being so constructed and arranged that pivotal movement of saidelement about one of said axes serves to efiect a coarse adjustment ofsaid part whilst movement about another axis serves to efiect a fineadjustment of said part, said pivotally-mounted adjustable elementcooperating with three points of pivotation, two of said pointsdetermining the axis about which said element pivots for effecting acoarse adjustment of tuning and the third point and one of said twopoints determining the axis about which said element pivots foreffecting a fine adjustment of tuning, a connecting member linking saidpivotally-mounted adjustable element and said adjustable part of saidresonator, the location and arrangement of said connecting memberrelative to said points being such as to determine the relative rates ofmovement of said part for coarse and fine tuning of said resonator, saidconnecting member engaging said adjustable element in a plane which isdifferent from the plane containing said points.

' NORMAN CHARLES BARFORD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,579,482 Jorgensen Apr. 6, 19262,263,184 Mouromtsefi Nov. 18, 1941 2,406,372 Hansen Aug. 27, 19462,439,387 Hansen Apr. 13, 1948

